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Title Efficient, Safe and Sustainable Traffic at Sea
Acronym EfficienSea
Contract No. 013
Document No. D_WP6_1_01
Document Access: Restricted
Dynamic risk management - user need
description
Deliverable No. D_ WP6_1_01
Date: 23.07.2009
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DOCUMENT STATUS
Authors
Name Organisation
Margareta Lützhöft Chalmers
Gesa Praetorius Chalmers
Anders Brödje Chalmers
Karl Bruno Chalmers
Reviewing/Approval of report
Name Organisation Signature Date
Tommi Arola FMA 30.7.2009
Document History
Revision Date Organisation Initials Revised
pages
Short description of
changes
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Executive Summary
In the last decade maritime traffic on the Baltic Sea has increased drastically. It is expected to
increase even more in the future leading to a traffic situation which is becoming a threat to the
safety of navigation and to the maritime environment (Sonninen & Savioja, 2005).
EfficienSea is a strategic project concerned with improving the efficiency, safety and sustainability of
the increasing maritime traffic in the Baltic Sea region. 17 organisations from six countries are
participating in the project, consisting of six work packages.
The study is part of Work Package 6 concerning “Dynamic Risk Management”. The work package
aims to develop and demonstrate different approaches to dynamic risk management. Part of this
work is the assessment of decision support tools used for the provision of vessel traffic service (VTS).
The following research questions were considered:
1. What characterizes decision making in the settings of a VTS centre?
2. What decision support tools are used today to provide vessel traffic service?
3. What user needs do VTS operators have today and how can these be included in the decision
support system development of the future?
Decision Support for a VTS
As part of the project several decision support tools used today for the provision of VTS were
studied. In VTS-centres decision support aids are often subsystems integrated in one large VTS-
system. These aids are used to support traffic control and monitoring, information gathering and
navigational assistance.
Following decision support tools were examined in the study:
- RADAR
- AIS
- GPS/DPGS
- ENC
- VHF radio
- Cameras
- Internet and mobile phones
Additionally, to highlight that decision support tools are not limited to be a technical solutions,
procedures, checklists and training of VTS operators and their impact on the operators’ decision
making were studied.
Study visits, expert interviews, a simulation, a focus group interview and a literature study were used
to collect data on VTS operators’ user needs. The collected data was analyzed by applying the
Recognition-Primed Decision (RPD) Model (Klein, 1993) of decision making in naturalistic settings.
What characterizes the decision making in the settings of a VTS centre?
VTS operators act based on experience, making it hard to actually single out different aspects that
influence the decision making. Thus, there is a variation of situations which are seen as typical and
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where the operators act on earlier experiences, creating a framework consisting of expectancies,
cues, plausible goals and typical actions.
During traffic monitoring the operators look for information that conflicts with their expectancies on
the traffic development. They use the information from various data sources to construct a dynamic
picture of the situation. Based on their working experience, both on board and on shore, the
operators have concepts on what is typical and what is not. As long as all the information is classified
as typical, their course of action is to let the traffic flow without interfering actively. Acting on the
situation, the operators make the decision on which information is needed by whom and when.
In order to assist a vessel with navigation the operator needs to infer more data from the context.
This might, for example, happen through conversations on the VHF working channel in the area
where the responsible VTS operator asks the bridge team for complementing information. The
communication is used to define what kind of advice or assistance a certain vessel needs. It is also
used to derive information on the status of the bridge team.
What makes the decision making process of navigational assistance vary from the one of information
service and traffic monitoring is that the operator needs to consider both the bigger picture and the
immediate surroundings while assisting in someone else’s decision process instead of just matching a
response to a typical situation. This means he/she needs to assess the situation without taking over
control, matching the advice or assistance to a specific vessel and crew in a specific context.
What decision support tools are used today to provide vessel traffic service?
Through several expert interviews, observations and a focus group interview it became clear that the
use of decision tools is highly dependent on contextual factors such as:
• Services offered by the VTS in the specific area
• Traffic density
• Geographical and hydro-meteorological conditions
• Manning levels
• Level of education and work experience of the operator
The results show that the need for decision support tools can differ from one VTS centre to another.
In some areas VTS operators also have to take responsibility for tasks not necessarily included in the
definition of a VTS. This makes it hard to define which decision support tools are actually used and
needed for the provision of VTS in a VTS area.
However, the results of this study show that most essential for a VTS operator is the VHF and the
RADAR. These two tools were also found to be indispensible and should always be working. Further,
parts of the AIS information transmitted were also identified as important for the provision of good
VTS service, e.g. CPA, TCPA, name, course and ETA. But nevertheless, all the experts mentioned that
there were problems with the reliability of AIS data displayed in the system.
Finally, the data collected in this study indicates that one of the key elements in the decision making
in a VTS centre is not any specific tool, but rather the experience the operators build up and
maintain.
What user needs do VTS operators have today and how can these be included in the
decision support system development of the future?
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Organisational user needs
In the study, aspects concerning the overall organisation of the maritime sector arose. It became
clear that a general goal and an overall scope for the work of the VTS must be defined. The main goal
should be safety. The organisation of the maritime sector should be aware of the importance of
creating a safety framework of guidelines which is VTS-centred. This includes a clear statement of
which services are included in the VTS. A VTS centre should not become an overall service centre for
all the events happening in a VTS area, e.g. VTS operators should not be forced to take fairway
maintenance records, answer to port alarms, organise the berthing of ships etc.
In addition, clear guidelines concerning the VTS education must be stated. A background as a Master
Mariner should be obligatory for all VTS operators. Communication skills and navigation knowledge
need to be improved and refreshed frequently to guarantee the best preconditions to provide good
service to the maritime community.
Technical user needs
The VTS operators emphasized that the right information must be presented at the right time. What
type of information this is and when it needs to be presented, depends on the context of use, e.g.
traffic density, geographical and hydro-meteorological conditions. The amount of information should
be matched to what is needed for the daily work of an operator. Future support system design
should bear in mind that decisions are often made based on pattern recognition.
Further, many operators expressed concern with regards to the trustworthiness of the information
displayed in the system, in particular with regards to AIS-based information. Operators must be able
to rely on the information which they base their decisions on. Doubts on the trustworthiness of a
data source lead to a time-consuming process of double checking. The validity and integrity of a data
source must be guaranteed or it needs to be removed from the system altogether.
Additionally, the experts stated that problems in the interaction between shore and ship arise by
having differences in the information displayed on shore and on the bridge. These differences must
be compensated for, or otherwise be managed, to facilitate the work of the VTS operators.
Summary of needs
1. Support familiarity in the information presentation to facilitate pattern matching for quick
and effective decision making
2. Support of communication to facilitate the interaction of the different players in the
maritime sector.
3. Support the building of trust through better and more effective communication between
shore and ship (content is more important than quantity)
4. Re-evaluating and defining the role and tasks of the VTS as service for the maritime
community with safety as the main goal
5. Need for a common “situation picture” so that bridge team and VTS operators can perceive
the same representations
6. Remember the non-technical resources such as experience, training, co-workers and
procedures
7. The validity and integrity of the data presented in the system must be guaranteed
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Table of Contents
Abbreviations/Definitions ..................................................................................................................... 10
1 Introduction........................................................................................................................................ 13
1.1 General introduction ................................................................................................................... 13
1.2 Aim............................................................................................................................................... 13
1.3 Document structure .................................................................................................................... 13
2 Background......................................................................................................................................... 14
2.1 History of the Vessel Traffic Service............................................................................................ 14
2.2 Vessel Traffic Services Today....................................................................................................... 14
2.3 VTS- personnel............................................................................................................................. 15
2.4 Support Systems used for Vessel Traffic Services ....................................................................... 15
2.4.1 RADAR................................................................................................................................... 16
2.4.2 Automatic Identification System (AIS).................................................................................. 16
2.4.3 Geographical Positioning System (GPS) and Differential Geographical Positioning System
(DGPS)............................................................................................................................................ 17
2.4.4 Electronic Navigation Chart (ENC) and Electronic Chart Display and Information System
(ECDIS) ........................................................................................................................................... 18
2.4.5 Cameras................................................................................................................................ 18
2.4.6 VHF-radio.............................................................................................................................. 18
2.4.7 Internet and mobile phones................................................................................................. 18
2.4.8 Non-technical decision aids: Procedures, checklists and training as decision tools ............ 18
2.5 Related Projects........................................................................................................................... 19
2.5.1 BaSSy .................................................................................................................................... 19
2.5.2 EMBARC................................................................................................................................ 19
2.5.3 MarNIS.................................................................................................................................. 19
2.5.4 SafeSeaNet (SSN).................................................................................................................. 20
2.5.5 PORTNET............................................................................................................................... 20
2.5.6 Gulf of Finland mandatory Ship Reporting System (GOFREP).............................................. 21
3 Theoretical Framework ...................................................................................................................... 22
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3.1 Naturalistic Decision Making (NDM) ........................................................................................... 22
3.2 Naturalistic Decision Making Settings ......................................................................................... 22
3.2.1 Ill-structured problems and uncertain and dynamic environment...................................... 22
3.2.3 Shifting, ill-defined and competing goals ............................................................................. 22
3.2.4 Action and Feedback Loops.................................................................................................. 23
3.2.5 Time pressure /stress and high stakes ................................................................................. 23
3.2.6 Multiple players, goals and norms ....................................................................................... 24
3.3 Recognition-Primed Decision Model (RPD Model) ..................................................................... 24
3.4 Usability defined by ISO 9241-11 “Ergonomic requirements for office work with visual
display terminals”.............................................................................................................................. 25
4 Method............................................................................................................................................... 27
4.1 Literature study ........................................................................................................................... 27
4.2 Simulation “eSim” ....................................................................................................................... 27
4.3 Study visits coupled with expert group interviews ..................................................................... 27
4.4 Expert interviews......................................................................................................................... 28
4.4.1 Eric Wagner .......................................................................................................................... 28
4.4.2 Adam Cowburn..................................................................................................................... 28
4.5 Focus group interview ................................................................................................................. 28
5 Results ................................................................................................................................................ 30
5.1 Study visit at the VTS-centre in Ymuiden .................................................................................... 30
5.1.1 VTS Ymuiden......................................................................................................................... 30
5.1.2 Work environment and equipment...................................................................................... 30
5.1.3 Training, experience and good service................................................................................. 31
5.1.4 Anomalies and near miss situations for VTS/SRS operators ................................................ 31
5.1.5 Problems/needs ................................................................................................................... 32
5.2 Study visit at the Hook of Holland and Traffic Centre Hook (17th April 2009) ........................... 32
5.2.1 Services and organisation at the T.C.H................................................................................. 32
5.2.2 VTS operators and workstations .......................................................................................... 32
5.2.3 Alarms................................................................................................................................... 33
5.2.4 Collision avoidance and safety margins ............................................................................... 33
5.2.5 Planning – short-term, long-term, proactive........................................................................ 33
5.2.6 Communication .................................................................................................................... 34
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5.3 Study visit at Sound VTS Malmö.................................................................................................. 34
5.3.1 The operators at the Sound VTS........................................................................................... 34
5.3.2 Working environment and equipment................................................................................. 34
5.3.3 Traffic anomalies, near miss and high risk vessels ............................................................... 35
5.3.4 Good service......................................................................................................................... 35
5.3.5 Communication .................................................................................................................... 35
5.3.6 Problems/Needs................................................................................................................... 36
5.4 Expert Interview with Eric Wagner.............................................................................................. 36
5.4.1 Service and manning levels at Helsinki VTS.......................................................................... 36
5.4.2 The VTS system..................................................................................................................... 37
5.4.3 Alarms................................................................................................................................... 37
5.4.4 Experience ............................................................................................................................ 38
5.4.5 Problems/Needs................................................................................................................... 38
5.5 Focus Group Interview ................................................................................................................ 38
5.5.1 Questions.............................................................................................................................. 38
5.6 Expert interview with Adam Cowburn ........................................................................................ 41
5.7 Result eSim .................................................................................................................................. 42
5.7.1 Planning................................................................................................................................ 42
5.7.2 Equipment ............................................................................................................................ 42
6 Analysis and Discussion ...................................................................................................................... 43
6.1 What characterizes the decision making in the settings of a VTS centre?.................................. 43
6.1.1 Traffic Monitoring................................................................................................................. 43
6.1.2 Information Service .............................................................................................................. 43
6.1.3 Navigational Assistance........................................................................................................ 43
6.2 What decision support tools are used today to provide vessel traffic service? ......................... 44
6.3 What user needs do VTS operators have today and how can these be included in the decision
support system development of the future? .................................................................................... 45
6.3.1 Organisational user needs.................................................................................................... 45
6.3.2 User needs concerning the technical system....................................................................... 46
6.3.3 Indications for future development ..................................................................................... 46
7 Conclusions......................................................................................................................................... 47
7.1 Trustworthiness........................................................................................................................... 47
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7.2 Information presentation............................................................................................................ 47
7.3 Organisational needs................................................................................................................... 47
7.4 Summary of needs....................................................................................................................... 48
7.5 Future Research........................................................................................................................... 48
References............................................................................................................................................. 49
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Abbreviations/Definitions AIS Automatic Identification System,a system that transmits certain information
about the ship (name, position, speed etc.) and receives the same information
from other AIS-equipped vessels in the vicinity.
AtoN Aids to Navigation
BaSSy Baltic Sea and Safety project
Boarding point A position where pilots board or disembark ships at sea.
CCTV Closed-circuit television, the transmission of signals from video cameras to a
specific place (as opposed to broadcast television).
COG Course over ground, the actual course a vessel follows (differs from heading,
which is the direction in which a vessel points).
COLREGS International Regulations for Preventing Collisions at Sea. The IMO “rules of
the road”, to be followed by vessels at sea
CPA Closest point of approach, an estimated point where the distance between
two vessels will be at a minimum.
DAMSA The Danish Maritime Safety Administration.
DSS Decision Support System
ECDIS Electronic Chart Display System, a navigation information system for vector-
based digital charts.
EMSA European Maritime Safety Agency, the maritime safety agency of the
European Union.
ENC Electronic Navigational Chart, term for official electronic charts produced for
use with an ECDIS.
ETA Estimated Time of Arrival, a measure of when a vessel is estimated to arrive at
a certain point
Fairway Fairway in the widest sense of the term refers to the water areas used for
shipping. It is however normally used in the sense of a cleared channel
intended for navigation.
FMA Finnish Maritime Administration.
GNSS Global Navigation Satellite System
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GOFREP Gulf of Finland Reporting System, a mandatory ship reporting system in the
Gulf of Finland.
GPS Global Positioning System, a system for satellite navigation.
GRT Gross Register Ton
HRO High Reliability Organisation
IALA International Association of Marine Aids to Navigation and Lighthouse
Authorities
IMO International Maritime Organisation
ISPS International Ship and Port Facility Security
MKD Minimum Keyboard and Display
MMSI Maritime Mobile Service Identity
NDM Naturalistic Decision Making, a theoretical framework for decision making
research, emphasizing the study of how people actually make decisions in
demanding situations.
OER Operational Experience Review
POS Pilot Ordering Service
RADAR Radio detection and ranging, an object detection system.
RPD Recognition-Primed Decision making, a decision making theory included in the
NDM framework.
SMA The Swedish Maritime Administration.
SMCP Standard Marine Communication Phrases
SOG Speed over ground, the actual speed of a vessel relative to the ground (can
differ from speed through the water).
SOLAS International Convention for the Safety of Life at Sea. IMO regulations
concerning the safe construction and equipping of ships.
SRS Ship Reporting System, a voluntary or mandatory reporting system for vessels
in a specified area. It collects and distributes information of importance for
the vessel traffic safety.
SSN SafeSeaNet, a European platform for maritime data exchange.
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VHF Very high frequency, a band of radio frequencies used for among other things
maritime communication.
UHF Ultra high frequency, a band of radio frequencies.
VTS Vessel Traffic Service, a shore-side service for vessel monitoring, navigational
assistance and information service.
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1 Introduction
1.1 General introduction
In the last decade maritime traffic on the Baltic Sea has increased drastically. It is expected to increase even
more in the future leading to a traffic situation which is becoming a threat to the safety of navigation and
to the maritime environment (Sonninen & Savioja, 2005). EfficienSea is a strategic project concerned with
improving the efficiency, safety and sustainability of the increasing maritime traffic in the Baltic Sea region.
17 organisations from six countries are participating in the project, consisting of six work packages
(application form, partner document). The work relates to the concept of e-Navigation, aiming to
harmonize collection, integration, exchange, presentation and analysis of marine information (IMO NAV
54). Decision support tools are one part of this, and as is it considered essential that the e-Navigaton
architecture is developed in accordance with top-down user requirements (IALA Recommendation e-NAV
101), it is also necessary to assess what the actual user requirements are. The following study is part of
Work Package 6 concerning “Dynamic Risk Management”. The work package aims to develop and
demonstrate different approaches to dynamic risk management. Part of this work is the assessment of
decision support tools used for the provision of vessel traffic service (VTS).
1.2 Aim
As part of work package 6 “Dynamic Risk Management” the aim of this study was to identify the user needs
that relate to decision support tools used today for providing vessel traffic service. Further, the study
focused on examining the overall needs of VTS operators today and in the future.
The following research questions were considered:
1. What characterizes decision making in the settings of a VTS centre?
2. What decision support tools are used today to provide vessel traffic service?
3. What user needs do VTS operators have today and how can these be included in the decision
support system development of the future?
1.3 Document structure
The report consists of seven chapters. Chapter 1 is a general introduction and presents the overall aim of
the study. A background including the history and definition of VTS as well as an overview on the decision
support tools studied is presented in chapter 2. Chapter 3 introduces the theoretical framework used for
the analysis of the collected data. In chapter 4 the methods used for the data collection are described. The
results of the data collection are presented in chapter 5 followed by an analysis and discussion in chapter 6.
Chapter 7 summarizes the overall conclusions and introduces areas for future research.
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2 Background Vessel Traffic Service (VTS) is a shore-side service implemented by a “Competent Authority to improve the
safety and efficiency of vessel traffic and to protect the environment” (IMO, res. A.852). The VTS operates
through VTS-centres with operators monitoring traffic, assisting in navigational matters and providing
information with the help of several decision support systems. Through the past years there have been
several studies concerning decision support tools for the maritime sector but most of them focused on the
technical aspects of such tools including possible enhancements and future applications rather than
applying a usability perspective in the analysis (Høye, Eriksen, Meland & Narheim, 2007; Grundevik, Wilske,
Huffmeister, 2009; Kharchenko, Vasylyev, 2004; Chang, 2004).
2.1 History of the Vessel Traffic Service
VTS was not implemented in one day; the need for this service arose through decades. All started with the
introduction of shore based RADAR stations in the late 1940s. Traffic management was very limited in that
time and RADAR stations were introduced to facilitate the effective use of port facilities. RADAR could
provide traffic images and it was possible to monitor the traffic to keep it flowing, especially in the port
areas and approaches. The first shore based RADAR was installed in 1948 in Douglas, Isle of Man, followed
by the ports of Liverpool and Rotterdam (IALA VTS Manual, 2002). The first steps towards what is nowadays
known as VTS were taken the 1970s. After several major oil spills, the pressure to protect the maritime
environment rose and resulted in a slow, but constant movement towards more organised co-operation
between pilots and RADAR chain operators.
On the initiative of the Governmental Maritime Consultative Organisation (IMCO), nowadays called IMO,
VTS was defined by adopting a resolution on the implementation of such a service. This resolution was
replaced by the IMO Assembly Resolution on VTS (A.857(20)) in 1997. A.857 states guidelines for vessel
traffic services (IALA VTS Manual, 2002). There are two different types of Vessel Traffic Services, coastal and
port or river services. A coastal VTS is responsible to assist with the safe passage of vessels through coastal
waters, especially when there is a high traffic density or if the area is difficult to navigate. Port or river
services assist vessels to navigate efficiently and safely when leaving or entering a port or while sailing
along a river. Nowadays there are more than 500 operational services worldwide (IALA VTS Manual, 2002).
2.2 Vessel Traffic Services Today
As mentioned above Vessel Traffic Service (VTS) is a shore-side system implemented by a “Competent
Authority to improve the safety and efficiency of vessel traffic and to protect the environment” (IMO, res.
A.852). There are three different types of services included in VTS: information service, navigational
assistance service and traffic organisation service. Depending on the geographical characteristics as well as
on the traffic density and pattern, the Competent Authority needs to consider which of the three services
are going to be provided by a VTS-centre in the area. The Competent Authority is defined by the IMO as
“the authority made responsible, in whole or in part, by the Government for vessel traffic safety, including
environmental safety, and the protection of the environment in the area” (IALA VTS Manual, 2002).
Information service is a service providing the traffic with all necessary information in good time.
Information can be any kind data concerning vessels’ positions, intentions, destinations as well as any
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information concerning the VTS-area, e.g. boundaries, radio channels, reporting points, hydro
meteorological facts etc. The information service is meant to “assist the shipboard navigational decision
making process” (IALA VTS Manual, 2002).
Navigational assistance service consists of two parts, navigational advice and navigational information.
Navigational information can contain:
• course and speed of a vessel
• positions identities and intentions of the surrounding traffic
• warning to specific vessels
• position relative to the fairway axis and way-points.
In the case of navigational assistance in form of navigational information the VTS contributes to the
decision making on board. In contrast to it, navigational advice includes are more active part for the VTS
operator as he/she is participating in the actual decision making. Navigational assistance service is given at
request. (IALA VTS Manual, 2002)
Traffic organisation service has the objective to prevent the development of dangerous situations and to
keep the traffic fluent, safe and efficient in the VTS-area. It is concerned with proactive planning of vessel
movements to avoid accidents and congestions. The traffic is monitored and governing rules and
regulations are enforced. In the areas where VTS is authorized to provide traffic organisation, the
instructions should be as clear and direct as possible, leaving only details of the execution to the vessel
(IALA Manual, 2002).
2.3 VTS- personnel
As mentioned above the VTS is operated by VTS operators. Depending on the geographical area and the
traffic density and pattern, an operator is responsible for providing service for either the whole area or a
certain sector. As the operator should be capable of providing all necessary information and even
navigational assistance and traffic organisation, most of the operators have a marine background (IALA VTS
Manual, 2002). Through the past decade IALA has stated guidelines, standards and recommendations for
the training of VTS operators, -supervisors and managers (e.g. Recommendation V-103 (1998)). Most focus
is on the so-called “On-the-Job Training”. After several basic courses the new operator is appointed to a
VTS-centre and is trained on the job by a certified VTS operator to acquire a thorough knowledge of the
area and the actions appropriate for providing VTS-service (IALA VTS Manual, 2002).
2.4 Support Systems used for Vessel Traffic Services
The following chapter is an outline of available support systems used today to facilitate the decision making
process of VTS operators. The outline will include both technical systems such as RADAR as well as non-
technical support, e.g. guidelines and procedures. In VTS-centres decision support aids are often
subsystems integrated on different layers in one large VTS-system. These aids are used to support traffic
control and monitoring, information gathering and navigational assistance. There are several
manufacturers, e.g. Atlas Elektronik, Saab Transponder Tech, Sofreglog etc., offering such systems. Design
as well as sources of information used in those systems can differ a lot between various VTS-centres
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depending on the size, the traffic density and the overall needs of the operators to be able to provide VTS
(IALA VTS Manual, 2002). A VTS-system is often referred to as a decision support system (DSS).
A Decision Support System (DSS) is an interactive system or subsystem designed to facilitate decision
making by combining data, documents, knowledge and/or models to identify and solve problems. In
general, DSS are computer-based information systems, which enhance a person’s or group’s ability to make
decisions. (dssresources.com) Although the different decision aids are normally integrated in one VTS-
system, each decision aid is going to be presented separately to underline its advantages and disadvantages
in use for VTS service.
2.4.1 RADAR
RADAR is one of the most important instruments used for navigation and traffic monitoring. It is short for
radio detecting and ranging. RADAR is based on actively measuring the surroundings. It uses high frequency
radio waves, which are reflected by objects and other hinders. These reflections are received by a RADAR
receiver and are used to identify hinders, objects etc. (www.ne.se). There are both ground based and ship
borne RADARs (Koester, Anderson & Steenberg, 2007). RADAR is a robust system and has been in use for
several decades. It has the advantage of being independent from other sources, e.g. databases, GPS, not
needing any other information input. Other decision aids in the maritime sector require data input from
other sources, e.g. AIS which needs a GPS-position. As the RADAR is independent from other sources it is
more reliable than other tools. It is a stable system and can be used in various weather types (Grundevik &
Wilske, 2007).
However, there are several disadvantages with this decision aid. To have a complete coverage of an area
several antennas are needed, which can be quite cost-intensive. Further, distance measurements are not
always correct so that it is hard to see how close different objects/vessels are to each other. Even
overshadowing, meaning that a vessel is not detected due to objects, other vessels etc. shielding it, is a
recurring problem, when vessels are near the coastline. When RADAR is used in bad weather conditions,
e.g. snow, rain or high waves, the quality of the information can be compromised. Further, one has to keep
in mind that RADAR on its own never can be used to identify a vessel. For identification the use of at least
one other decision tool is needed, either VHF radio or AIS (Grundevik, Wilske, 2007).
2.4.2 Automatic Identification System (AIS)
The automatic identification system was introduced in 1995 with the aim of avoiding collisions and assisting
the VTS. It provides mariners with on-line static and dynamic data of other vessels’ behaviour. It is the first
information source in the maritime traffic surveillance which is dependent on information transmitted by
other ships. Today it has also become one of the most important tools for traffic monitoring. Via a VHF
frequency a vessel’s ID, position, course, heading and speed is transmitted to other vessels and/or to
receivers onshore. AIS offers the possibility to send important information concerning e.g. a port or dangers
to navigation. AIS is mandatory for all vessels larger than GRT 300 (Koester, Anderson & Steenberg, 2007).
An AIS-message contains three types of information: static (MMSI-number, IMO-number, call signal, name,
ship type), dynamic (position, course, speed, heading, rate of turn, navigational status, time) and journey
related (type of goods, actual draft, destination and ETA) information. The interval in which the message is
sent differs depending on the size, the cargo and the speed of a vessel. Table 1 shows the reporting interval
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depending on a vessel’s behaviour. AIS is ship borne, but it can also be placed on a non-vessel (Koester,
Anderson & Steenberg, 2007).
Table 1:
Ship status Reporting interval
At anchor or berth 3 min
0-14 kn 10 sec
0-14 and altering course 4 sec
14-23 kn 6 sec
14-23 kn and altering course 2 sec
>23 kn 2sec
>23 kn and altering course 2 sec
The AIS-information is normally presented as digital information either on small separate displays (MKD) or
as symbols with vectors overlaid on RADARs or in an ECDIS. Normally the operator can choose which
information should be displayed and in what way. Further, the AIS can be used for online presentation of
the traffic situation, replay of historical data, statistics, accident investigations, risk analysis and for
optimization of the placement of aids to navigation (AtoN). There are some common errors linked to the
AIS caused by both operators and the manufacturers. These errors include failures in the man-machine
interaction, installation errors, wrong static data (wrong input of IMO- or MMSI-number) and errors in the
GPS signal (Koester, Anderson & Steenberg, 2007).
Although AIS offers a faster information update in a better quality than the RADAR and is more
independent from visibility and weather conditions, it is highly depending on correct GPS-data. If the data
the vessel is receiving from the GPS is incorrect, so is the information transmitted to the VTS-centre and to
other vessels. Another problem with the AIS is that it is not mandatory for all vessels, which leads to
difficulties in detecting smaller vessels and yachts. However, if AIS was mandatory on all types of ships, it
would probably still be hard to detect any vessel as there always is a risk of cluttering screens (Grundevik,
Wilske, 2007).
2.4.3 Geographical Positioning System (GPS) and Differential Geographical Positioning System
(DGPS)
Today the GPS is the only fully functioning global navigation satellite system (GNSS). It has the purpose to
give positioning with a global coverage. It is built up from 24 medium Earth orbit satellites that enable a
GPS-receiver to determine its location, speed, direction and time. A GPS-receiver requires signals from at
least four satellites at one time to be able to calculate a reliable three-dimensional position. As the GPS can
provide a three-dimensional position 24 hours a day and independent of the weather conditions, it is one
of the cornerstones of navigation world-wide. There are some limitations to the GPS. As GPS always needs
a clear line of sight between the receiver and the satellite, its information can be unreliable if an antenna is
shielded by an object. There have also been some problems with the range and the accuracy of GPS. To
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compensate for these problems, differential GPS (DGPS) is used. DGPS is based on shore-based reference
stations sending out signals which are used to correct the position obtained by the GPS-signal (Koester,
Anderson & Steenberg, 2007).
2.4.4 Electronic Navigation Chart (ENC) and Electronic Chart Display and Information System
(ECDIS)
Electronic navigation charts include information about routes, depths, shoreline etc. ENC is the name for
the official electronic charts. These charts are based on vectors and are in digital format, which means the
position of each object in the chart is shown individually. ENCs are presented in a so called Electronic Chart
Display and Information System (ECDIS). In an ECDIS various navigational tools can be integrated based on
the need of the user (Bjelfvenstam, 2007). In the settings of a VTS the information from different sensors
such as AIS, RADAR etc. is presented on an ENC in the VTS system.
The ECDIS are complex systems and as different types of information can be integrated in such systems
they need an adequate amount of training in order to be operated correctly. Aside from its complexity the
system depends on different databases to be able to get access to updated charts (Grundevik, Wilske,
2007).
2.4.5 Cameras
Video cameras are commonly used for traffic monitoring. Normally those cameras are CCTV (Closed-Circuit
TeleVision). These cameras are located along the fairways in a VTS-area. A VTS operator can zoom in and
out on a spot as well as cameras normally are moveable in different directions. Although cameras are
important tools for traffic monitoring, some state (Bjelfvenstam, 2007) that they are only useful in daylight
and in good visibility.
2.4.6 VHF-radio
Very high frequency radio is used mainly for voice communication between the VTS-centre and the vessels
in the official VTS-area. The VHF is used for distributing information to the vessels in the VTS-are as well as
to keep track of the traffic movements (e.g. by calling a vessel when it passes a reporting line).
2.4.7 Internet and mobile phones
During the past years the use of Internet and mobile phones as a communication means between vessels
and the VTS has increased. The development of broadband Internet enables the exchange of different kinds
of information, e.g. exchange of RADAR pictures (Koester, Anderson & Steenberg, 2007).
2.4.8 Non-technical decision aids: Procedures, checklists and training as decision tools
The decision support tools named above are all based on the idea that such a decision aid needs to be
technical, usually based on information presentation on a digital display. This view on decision support
tools is very limited. Operators do not simply focus on their computer screens but work interactively with a
large system, following guidelines, procedures and checklists during their work (e.g. emergency
procedures). Thus all kinds of guidelines, procedures, recommendations and checklists can be viewed as
decision aids, too. They all constrain the operator’s decision and actions and help to make sense out of the
information presented in the VTS-system. Also training can be seen as a tool to shape decision making and
is therefore also part of the decision aids a VTS operator has access to. Even experience seems to have a big
impact on how decisions are made in such dynamic settings as the working context in a specific VTS-centre.
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When focusing on new solutions in the field of decision support systems, one should focus on defining how
decisions are made in real life settings instead of deciding which technical solution is appropriate to
improve the decision making of VTS operators. Training, changing procedures, implementing new checklists
or even the redesign of the workplace can also improve decision making processes (Roberts, Bea; 2001).
Another very important decision making resource can be one’s co-workers, as plenty of evidence from
other domains shows. Research within the so-called high-reliability organisation (HRO) framework
emphasises on the role of individual people and their relations to their tasks and to each other in making
decisions and maintaining safety in very complex and sensitive organisations, for example nuclear-powered
aircraft carriers (see e.g., Roberts 1990; Weick & Roberts 1993). Extensive field work by Sanne (2003) within
the air traffic control domain also shows the importance of working together with people who share a
common orientation to the task at hand, in order to reach overall goals. Sanne’s results also show the
importance of giving people who work together the ability, time and motivation to be attentive to the
performance of each other. These are just two of many possible examples highlighting the importance of
one’s colleagues as a decision support resource.
2.5 Related Projects
During the past years there have been several projects concerned with the development of different
approaches to enhance the efficiency and safety of maritime traffic.
2.5.1 BaSSy
The BaSSy (Baltic Sea Safety) project was a research project centred on the importance of safe, well-
organised shipping in the Baltic Sea. Within the project there were several focus areas, such as the
development of a Formal Safety Analysis (FSA) framework to estimate the consequences of collisions and
groundings, a study of the design of ship bridges from a human-machine interaction perspective and, most
relevant in this context, a Man-Technology-Organisation profiling of a VTS centre, design of a decision
support concept for collision avoidance and an analysis of the risk reducing effects of safety measures such
as traffic separation zones. To include results derived and lessons learned in this study an expert interview
with Eric Wagner was conducted. Its results will be presented later in the report. Further, as information
from the project will be fed into EfficienSea by the project partners involved in the BaSSy-project.
2.5.2 EMBARC
EMBARC was a maritime safety research project with a multitude of different goals and objectives, with the
general objective being o demonstrate how the safety and efficiency of maritime transport is improved by
the VTMIS (Vessel Traffic Maritime and Information Services). Most relevant for this report is the
conclusion that all European waters should be a single reporting area, the introduction of the High-Risk
Vessel concept, and the idea that Vessel Traffic Management centres, including both VTS and search-and-
rescue functionality, could be beneficial.
2.5.3 MarNIS
A third relevant project is the MarNIS project, which had the general objective of improvement of safety
and the protection of the environment. It has many things in common with EMBARC, including the focus on
VTM’s and the High-Risk Vessel concept. MarNIS also examined the role of AIS and long range tracking in
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the monitoring of such HRV’s. MarNIS also focused on the exchange and dissemination of maritime
information.
2.5.4 SafeSeaNet (SSN)
SafeSeaNet (SSN) is a European platform for maritime data exchange between the Member States’
maritime authorities introduced on behalf of the Directive 2002/59/EC. The Directive stated the goal of
establishing a computerized data exchange system in the Member States. Since October 2004 the European
Maritime Safety Agency (EMSA) has been responsible for managing the system and the cooperation
between the different members. The political responsibility lies with the Commission
(www.emsa.europa.eu). SSN collects and contributes various kinds of data concerning vessel traffic
monitoring, dangerous cargo details, results of ship inspections and information related to ship waste and
cargo residue. It relies on a tree-like structure out of local Competent Authority, national Competent
Authority and the central index (www.emsa.europa.eu).
SSN is based on an internet solution with a distributed database. The core part is an XML-messaging
system, which is used to transfer data between the data provider and the data requester. The system itself
acts like hub providing information based on references. These references are central indexes which can be
compared to links. Instead of storing all information, SSN just safes a reference to where the information is
located. SSN can be used 24 hours a day all year long. In January 2008, 21 Member States were involved as
well as Norway and Iceland on both local and national level. (www.emsa.europa.eu)
2.5.5 PORTNET
PORTNET is an information system providing a collection of all authority notices required for ships arriving
or leaving a Finnish port. It is a telematic system, combining a telecommunication and information system
with an internet-based user-interface. PORTNET is a national single window facility that can be accessed
through the Internet. PORTNET is also responsible for the distribution of information to all concerned
parties. PORTNET is managed by the Finnish Maritime Administration (FMA) but it is owned by the
PORTNET-community, a community consisting of the FMA, Custom’s and the 20 largest ports in Finland
(Bäckström, 2005).
PORTNET is an internet-based application with operative time-table and cargo information concerning the
vessel traffic in the Finnish area of the Baltic Sea. It is available 24 hours a day. PORTNET is accessed
through a homepage www.portnet.fi which also contains other applications connected to it. Accessibility is
based on registration and on the rights granted by the PORTNET-community giving only authorities full
access to the portal and all its applications. In 2005 PORTNET had about 2000 registered users. (Bäckström,
2006). One of the parts of PORTNET not needing any registration is the intermodal portal. It contains
information regarding the vessels’ time-tables, Custom numbers and authority notices. That means e.g.
advance notice of arrival of a vessel, security notice from vessels (ISPS), cargo declarations etc. Further,
different authority decisions can be downloaded as pdf-forms, e.g. ISPS-notice regarding ship security
(ibid).
As PORTNET is owned by a community, all decisions regarding the system are distributed among the
responsible parties. All new information is handled using the web-interface. The information is provided by
ship agents and captains, pilots, ice-breakers, VTS and the ports themselves. All information is even linked
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to the SafeSeaNet-index server. On the national level PORTNET is used by FMA, the Frontier Guard,
Customs, Marine defence forces, ports and the Ministry of Agriculture. (ibid). The advantage of PORTNET is
that it can be used in combination with an AIS-base station network. The AIS is directly being connected
and matched to different port calls, which can be used for estimating a vessel’s arrival with close to one
minute accuracy (ibid).
2.5.6 Gulf of Finland mandatory Ship Reporting System (GOFREP)
Due to a drastic increase of traffic in the Gulf of Finland the Estonian, Finnish and Russian maritime
authorities implemented the project of the Gulf of Finland mandatory Ship Reporting System (GOFREP) in
2004 (Sonninen & Savioja, 2005). The purpose of the GOFREP-system is to contribute to safety of
navigation through and across the GOFREP-area, increase the protection of the maritime environment and
to monitor compliance with regulations for preventing collisions at sea (www.fma.fi). The GOFREP system is
operated by three shore-based facilities at Tallinn Traffic, Helsinki Traffic and Sankt Petersburg Traffic. It
has primary and secondary tasks, some of them less frequent depending on the difference between
summer and winter operations.
Primary tasks are:
• the reception and distribution of relevant information from and to the vessel traffic
• monitoring vessel traffic, e.g. observing dangerous encounters or breaches of regulations.
• providing advice and information about navigational hazards or weather conditions
Secondary tasks are:
• reporting of breaches to responsible authority
• providing information for organisations not directly part of the system, e.g. port operators, shipping
agents.
The key element of the GOFREP-system is the communication between operators in the three participating
countries, which even has impact on the decision making onboard a vessel (Sonninen & Savioja, 2005). The
GOFREP system was developed based on human-centered design principles. During four workshops VTS
operators from Estonia, Finland and Russia participated in simulations to test different scenarios (Sonninen
& Savioja, 2005).
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3 Theoretical Framework
In the following chapter the theoretical framework for this report is presented.
3.1 Naturalistic Decision Making (NDM)
Naturalistic decision making emerged in the 1980ies based on findings from decision research in real life
settings. In field studies researchers found that decisions in high stake situations and under time pressure
were not made based on the idea of a decision-tree where a single decision maker evaluates different
alternatives according to the expected outcome. It was found that people in such situations rather make
decisions based on prior experience. (Klein, 2008). Instead of focusing on a certain decision event,
containing a moment of choice, considering alternatives and considering consequences, NDM focuses on
the situation assessment a decision maker makes in a specific situation. Studies showed that less than 20%
of all decisions made by people actually involve concurrent deliberation with more than one alternative or
cause of action was considered and contrasted. (Klein &Calderwood, 1991). In the following part
naturalistic decision making settings are going to be presented. Each setting will be applied to the VTS
domain.
3.2 Naturalistic Decision Making Settings
Naturalistic decision making settings are characterized by eight different features which are hard to explain
for traditional decision making strategies: Ill-structured problems, uncertain and dynamic environment,
shifting, ill-defined or competing goals, action and feedback loops, time pressure, high stakes, multiple
players and organisational goals and norms (Orasanu & Connolly, 1993). Generally these settings are
applicable in the shipping and VTS domain.
3.2.1 Ill-structured problems and uncertain and dynamic environment
Normally the problems a decision maker is confronted with are not well defined. They need to be
recognized by the decision maker and he/she often needs to take an active part to develop come up with
hypotheses to develop options of possible reactions towards a problematic situation (ibid). People often
find themselves in situations where information to be considered for the decision making is incomplete.
Not all information is necessarily available and as time proceeds the dynamic environment will change,
increasing the uncertainty of the situation (ibid).
The settings for the work of VTS operators are dynamic and uncertain. As the traffic image changes so does
the information that an operator has at hand to make decisions, creating a constantly changing situation.
Further, the information that the operators have at hand, can never completely display every detail of a
situation. There are always cases of incomplete or wrong AIS-messages, RADAR overshadowing or simply
technical malfunctioning of parts of the decision support systems used at a VTS. The operator therefore
needs to deal with both dynamic settings and a certain amount of incompleteness of information.
Therefore one can say that VTS operators concerns in the daily work do not normally appear well-
structured.
3.2.3 Shifting, ill-defined and competing goals
Outside of a laboratory it is seldom the case that there is just one specific goal or value influencing the
decision maker in his/her choices. It is often the case that there are shifting and competing goals, or even
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goals that are embedded in each other. This is especially tricky when new goal and values are introduced as
the situation is constantly changing. Further, there can be discrepancies between individual and
organisational goals and/or values providing yet one more level to take in consideration when making a
decision (ibid).
In their daily work VTS operators are often confronted with shifting, ill-defined and competing goals, an
example is safety as a goal which is competing with the schedule and time-keeping. All vessels in the area
have intentions and goals that they are following. It is up to the operator to understand those goals and to
organise the traffic so that it is sailing fluently and safely at the same time that all actors need to be
satisfied.
3.2.4 Action and Feedback Loops
In contrast to more traditional approaches, naturalistic decision making is interested in series of decision
events over time. The focus is on how these series are used to solve a problem or to get more information
on it, or even both, e.g. physicians choosing a treatment plan, not just a single isolated treatment. Often
the different decision events in such a series are used as feedback loops by the decision maker, changing
his/her course of action depending on new information obtained by earlier mistakes. How helpful new
information is for the decision maker derives from how tightly actions and situation outcomes are coupled
(ibid).
As stated above VTS operators need to take an active part in detecting conflicting or risky situations in the
traffic picture. An operator also needs to anticipate possible future accidents to create a safe and fluent
traffic situation. As one decision of an operator will probably affect more than just a single vessel, the
decisions made by one, should be treated more like a series of actions instead of isolated decisions. That
means that the operator uses the changing information as a form of feedback loop for his/her decisions
and actions with the possibility to correct the course of action depending on new information obtained
from the decision support tools.
3.2.5 Time pressure /stress and high stakes
A core aspect in naturalistic decision making is that nearly all decisions need to be made under conditions
where time is limited. This leads to situations in which the decision maker may experience personal stress,
increasing the risk of exhaustion and loss of vigilance. Further, to be able to make a decision under time
pressure one needs to develop a strategy. Research has shown that people tend to shift their thinking to
less exhausting decision strategies when dealing with time pressure (Payne, Bettman & Johnson, 1988 as
cited by Klein, 2003), definitely not turning towards strategies based on deliberation. Klein’s (1998)
research on fireground commanders showed that 80% of all decisions are made in less than one minute
which shows that it is impossible to consider several alternatives and to evaluate them. In the field of
naturalistic decision making the stakes normally matter for the decision maker which likely leads to a
situation where the participant feels personal stress while trying to achieve a good outcome as poor
decisions can lead to enormous cost, e.g. economic loss, loss of lives (Orasanu & Connolly, 1993).
In maritime settings a decision maker needs to deal with high stakes most of the time. If a poor decision is
made one or more vessels might collide, ground or worse; people could get injured. Sometimes just
seconds decide whether an accident happens or whether it can be prevented. This puts a lot of pressure
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on the VTS operator who is responsible for monitoring the traffic and providing the right information.
Additionally to high stakes and stress, there are strong organisational settings for a VTS with goals and
norms concerning safe and efficient traffic management in the fairways of the Baltic Sea. Rules and
guidelines as well as recommendations for the work stated by organisations like IALA, IMO, EMSA or local
authorities generating overall values for the working settings.
3.2.6 Multiple players, goals and norms
In real life decision making it is seldom that just one single individual is engaged in the decision making
process. It is rather the case that several individuals/parties are engaged in the decision making together,
with people or groups assigned to a specific decision making role in the process. One difficulty with this
characteristic of naturalistic decision making settings is that it is important to make sure that all parties
have access the information needed to share an understanding of common goals and the situational status
(Orasanu & Connolly, 1993).
There are always multiple players engaged in the decision making carried out at VTS-centres. Actors such as
a Harbour Master, Lock Master, pilot, VTS operator, captain of a vessel and his agency might all have
completely different goals which they act on in a certain situation. The VTS operator then needs to solve
upcoming conflicts by planning ahead and trying to satisfy the other parties’ needs.
3.3 Recognition-Primed Decision Model (RPD Model)
The RPD model was developed by Klein and associates in the late 1980ies. It is one of several models
dealing with the aspects of decision making in naturalistic settings and focuses on the importance of
recognizing a situation and applying pattern matching to decide on a course of action. In their research
Klein and his associates tried to analyze professionals’ decision making, e.g. fireground commanders,
nurses (Klein, 1998). Klein defined a decision as “choice point” where reasonable options exist and the
expert might select another option. The selection is not necessarily a conscious action, but as long as there
were different options available, a decision was made. Data from research on fireground commanders
indicated further that there was no deliberation about different options; neither were they considering
more than one alternative. Commanders could build a “good course of action” even from the moment they
were confronted with a situation (Klein, 1998).
Due to experience the commanders could focus on familiarities between the situation they were presented
with and earlier situations they had been through. These familiarities helped to derive a reasonable
reaction without the need to deliberate about different alternatives as the situation was identified as
prototypical (Klein, 1998).
The Recognition-Primed Decision (RPD) model focuses on two aspects of decision making, first the way that
decision makers identify the situation to be able to choose a course of action and second, the evaluation of
the chosen course of action by mental simulation. Klein (1998) identified three different variations of the
RPD model. Variation 1 focuses on how the decision maker recognizes the situation as typical and familiar,
variation 2 on how a situation is diagnosed and variation 3 deals with how the decision maker uses mental
simulation to evaluate the outcome of a possible course of action.
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Figure 1: The Recognition-Primed Decision Model
Variation 1 is a simple match. The situation is recognized as familiar and/or typical and the decision maker
proceeds to take action. When the situation is recognized the decision maker also recognizes the course of
action that is suitable. It is a reaction based on cues and patterns as it is not just the situation which is
recognized but also cues, goals, expectations and actions. (Klein, 1998) In the daily work of a VTS operator
variation 1 decision making occurs when the operator is conducting tasks like e.g. calling a vessel which is
passing the reporting line, informing the traffic about weather conditions or the water level in a fairway or
channel.
As named above, variation 2 focuses on diagnosing a situation. This means that the decision maker needs
to attend a situation actively as information obtained from it might not clearly fit a pattern. There is a need
to acquire more information about the situation to be able to diagnose it and to derive a course of action.
Variation 2 also accounts for situations where the outcome does not match the decision maker
expectancies. The decision maker will then try to respond by checking his/her interpretation, matching
what fits best to the situational features. One could say that the decision maker is “deliberating about the
nature of the decision” (Klein, 1998). An example of variation 2 decisions in the daily work occurs whenever
a VTS operator is monitoring the traffic and a vessel does not behave as expected. This might include, but is
not limited to, situations such as vessels passing very close to each other, ships leaving the fairways or
coming close to hot spots. The operator needs to take a closer look and analyze the situation further to be
able to react. He/she needs to be active and does not just react towards a situation but needs to evaluate
it.
Variation 3 focuses on mental simulation for evaluation of a course of action. The decision maker uses the
heuristic strategy of mental simulation to imagine how a specific course of action is going to influence
people, objects and the situation itself. This strategy is used to predict the future or to account for events in
the past. It is strongly coupled to experience (Klein, 1998). Variation 3 decisions are those which need a
closer evaluation in form of mental simulations of a specific course of action. These decisions occur
whenever a VTS operator is involved in planning his/her work. Based on the traffic picture presented on the
display the operator is using mental simulation to determine how the traffic is going to develop in the
nearer future. This includes evaluating the traffic picture by taking into account where vessels are heading,
how fast they are, what cargo they are carrying etc.
3.4 Usability defined by ISO 9241-11 “Ergonomic requirements for office work
with visual display terminals”
Usability is the “extent to which a product can be used by a specified user to achieve specified goals with
effectiveness, efficiency and satisfaction in a specific context of use.” (ISO 9241-11)
ISO 9241-11 defines usability as something that enables a user to achieve goals in a specific context. It is
defined by emphasizing on assessing the whole work system in naturalistic settings. Further, ISO 9241-11
attempts to introduce a framework, which can be used to measure usability of certain system components
as well as the usability of the overall system. (ISO 9241-11). ISO 9241-11 introduces three concepts for
measuring usability; effectiveness, efficiency and satisfaction. Effectiveness measures the accuracy and
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completeness with which a user achieves specific goals. Accuracy and completeness can for example be
measured by quality and quantity output. (ibid)
Efficiency focuses on the amount of resources used in relation to the effectiveness with which a user
achieves his/her goals. Resources in this case might be time, physical and mental energy spent on a task
and/or the material and financial cost of it. (ibid). Satisfaction is defined as “freedom from discomfort”. It
can be measured in terms of attitudes that users have towards a product. It is the user’s response to the
interaction with a product and it can be assessed by both subjective and objective measures, e.g.
observations, questionnaires, attitudes, opinions. (ibid)
Another important aspect in the above definition of usability is the focus on naturalistic setting or what is
called the “context of use”. It consists of users, tasks, equipment and the physical and social environment
and states indirectly that it is not the product but the context of use itself, which influences a product’s
usability (ibid). In this report the focus is primarily set on the context of use and the user satisfaction
defined by this ISO-standard to develop user needs for VTS operators today and in the future.
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4 Method This chapter presents the methods used for the data collection. As the aim of this study was to get insights
on VTS operators’ user needs different methods were used to obtain data. A literature study, a simulation,
a focus group interview and expert interviews were used during the collection.
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Figure 2: Data collection process
4.1 Literature study
To get an understanding on decision support tools used today a literature study was conducted. Its
objective was to give a state-of-the-art review on existing decision tools as well as to summarize lessons
learned and problems identified in other research projects, e.g. BaSSy, MarNis, EMBARC, SafeSeaNet. The
results of the literature study are included in the background chapter of this report.
4.2 Simulation “eSim”
During two days in March 2009 a day in the Sound was simulated at the Chalmers University of Technology.
The simulation was part of the work package 4 in EfficienSea and aimed to collect data to concerning user
needs as well as to analyze and explore communication and information flow among the actors of the
scenario. The simulation consisted of two three-hour long scenarios in the Sound between Denmark and
Sweden. It took part at the Chalmers University of Technology in Gothenburg and three bridge setups were
used. The bridge setups represented different vessels (cruise ship, tanker, coaster). Aside from different
vessels, the Port Authority (Port of Copenhagen-Malmö) a pilot (Drogden Pilot), VTS (SOUND
VTS/SOUNDREP), Lyngby Radio and JRCC were part of the simulation. All participating actors were
professionals and they were asked to act as close as possible to reality. As mentioned above, the simulation
had two parts, one baseline normal scenario and one baseline busy. The scenarios were constructed based
on a 24 hour AIS recording of the traffic in the Sound (report WP 4.2, ).
All radio communication during the simulation was recorded. Additionally every actor had one observer
using contextual inquiry. Contextual inquiry is a method used in social science research as well as in
software development and aims to understand the real environment people work. Observations are
combined with questions giving the observer an opportunity to get insights on a person’s daily work and
working routines. This method can be used to gain information on peoples’ attitudes, needs and problems
they face (Kuniavsky, 2003). All observations in the simulation were noted down in a software analysis
platform (CITE).
4.3 Study visits coupled with expert group interviews
To obtain deeper knowledge on the actual user needs of VTS operators three different study visits to VTS-
centres were conducted (VTS Ymuiden, Traffic Centre Hook of Holland, Sound VTS). Each study visit was
coupled with an expert group interview, in which two or more operators answered a set of questions. The
questions were openly formulated and dealt with a variety of topics (communication, good/bad service,
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anomalies and conflicting situations, use of decision support in daily work) concerning a VTS operator’s
work. Each topic was discussed with the help of one or more nondirected and follow-up questions.
Aside from interviewing experts in their daily work environment, the study visits also aimed to get a better
understanding on what technical equipment is used today to provide vessel traffic service in different areas
and what needs there are today that have to be addressed in the future. During each visit, the operators’
working environment was observed and the operators were asked questions, similar to a contextual
inquiry. During the study visit notes were taken while observing and interviewing the experts. On two of
the three study visits, presentations by the experts were held. All data collected was evaluated by
summarizing the interviewees comments and answers to a specific topic.
4.4 Expert interviews
4.4.1 Eric Wagner
As part of the state-of-the-art review on decision support system used for vessel traffic service, Eric Wagner
was interviewed as an expert. He participated in the BaSSy-project and conducted an operational
experience review (OER) at the Helsinki Traffic Centre, including an extensive task analysis of the work of
VTS operators. The interview was a semi-structured interview with nondirected and follow-up questions.
The aim was to get a deeper understanding for the different tasks VTS operators do during their daily work.
Further, the interview aimed at gaining more knowledge about the work of the BaSSy-project concerning
VTS. During the interview notes were taken which were evaluated afterwards. The answers were
summarized in different topics.
4.4.2 Adam Cowburn
To get a better insight on the education of VTS operators Adam Cowburn was interviewed. He has
background in behavioural studies and communication and has been working with the SMA concerning the
VTS education for several years. The interview was semi-structured and followed an interview guide
completed by follow-up questions. It took approximately 30 minutes and was recorded. The evaluation of
the interview is based on a verbatim transcription made after the interview.
4.5 Focus group interview
A focus group interview was conducted at the Aboa Mare, the Maritime Institute of Åbo Swedish Maritime
School. Focus group interviews are used to collect data concerning firsthand experiences, motivations,
values, priorities and desires as the participants state and discuss their opinion on a specific topic. This
interview form was developed in the 1930s and is used in various areas from social sciences research to
software engineering (Kuniavsky, 2003). In this study the focus group interview was used to gain further
insights about the overall user needs of VTS operators concerning decision support tools now and in the
future.
Seven men and one woman participated in the focus group. All were experienced VTS operators who were
taking part in an education for becoming On-the-Job training Instructors. The participants came from
different VTS-centres all over Finland (GoFREP, Helsinki, Bothnia, Archipelago, Kotka, Hanko) and had all
several years of experience working as VTS operator. Prior to the interview the participants received
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information on the project, the aim of the study and were asked to sign consent forms. After signing the
form, the participants were presented with three different questions.
1. Rank the following decision support tools according to their importance for your daily work!
Which one is most important, which one least?
• VHF
• CCTV
• Telephone/mobile phone
• GPS/DGPS
• AIS
• RADAR
• ECDIS
• Hydro meteorological information
• Databases, e.g. PortNet (please specify which ones)
• Internet
2. What characterizes a conflicting situation?
3. How would you define “good VTS-service”?
The participants were asked to think about and make notes on one question during five minutes
individually or until everyone agreed to be ready. Then the question was discussed openly in the group.
During the group discussion the different opinions and comments were recorded by writing them onto a
whiteboard. Aside from a moderator, there was one additional observer present taking notes during the
focus group interview. All notes taken by the operators were collected at the end of the interview. The
notes from the whiteboard were photographed. After the interview all notes were evaluated and
summarized according to the questions asked during the focus interview. The notes were evaluated by
comparing them to results from the study visits as well as by analyzing them in connection with the RPD
model.
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5 Results The following chapter of the report presents the results of the data collection. Data was collected through 3
study visits at different VTS-centres, a focus group interview with Finnish VTS operators and two expert
interviews.
5.1 Study visit at the VTS-centre in Ymuiden
The VTS Ymuiden is located in the Harbour Operation Centre (HOC) on the south bank close to the port of
Ymuiden. It offers different maritime services for vessels approaching the Sea Ports of Amsterdam
(Ymuiden, Velsen-N, Beverwijk, Zaandam and Amsterdam). In the HOC several services have been
centralized and can are offered to all traffic within the VTS-area. The VTS-service in the area is managed by
the Port of Amsterdam, as it is the largest of the Sea Ports, on behalf of the Central Nautical Management.
The Port itself is owned by the municipality of Amsterdam and is part of the Nautical Sector. VTS-services
are part of the traffic organisation department within the nautical sector. Beside VTS-services, a lock
service, the hydro-meteo advice service Ymuiden (HMAIJ), the pilot service and vessel movement reports
and administration are part of this department and are provided by the HOC.
5.1.1 VTS Ymuiden
VTS Ymuiden is responsible for traffic organisation, including planning and coordination as well as
monitoring vessel traffic. It also offers information services. All traffic approaching any of the ports needs to
pass the locks at Ymuiden and is handled by this VTS-centre. The centre is located at the entrance to the
Nordzeekanal which is the channel linking the North Sea with the ports. The HMAIJ is a service part of the
VTS responsible for tidal prospects, monitoring high tides and low waters and publishing tide-windows for
deep draught vessels. This data is important to guarantee the traffic flow on the entrance to the Sea Ports
of Amsterdam. Navigation assistance and advice in the VTS-area is a responsibility of the pilot organisation
which is also located in the HOC.
5.1.2 Work environment and equipment
The work environment is unique as it unites pilots, VTS operators, pilots, ship reporting administration and
port authorities in one space, the Harbour Organisation Centre (HOC). This centralization of services makes
it possible to exchange information on vessels, weather and other facts of concern among all actors and
services located in the HOC.
The VTS operators sit in line to each other in the same room as the Chief Pilot, Chief VTS1 and a shore-based
pilot. Although there are a lot of different advantages, e.g. possibility to direct information exchange
between organisations and services, it was mentioned by the Chief VTS operator that the level of noise due
to communication can be disturbing, especially during dense traffic hours when there is lots of
communication on the VHF-radio as well.
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1 Local job description for the officer at duty; VTS supervisor
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Figure 3: Three VTS operators and the operator of the Port of Amsterdam at the HOC
Each workstation is height adjustable and has six computer screens displaying information. Two screens
show the VTS-area , one the lock status reporting system, one the vessel reporting system, one pictures
from the cameras located at the locks and one displays weather and tidal information. Further, a work
station is equipped with two keyboards, for entering information into system, a VHF-station with a
microphone, a telephone and a pair of speaker.
The VTS operators and shore-based pilots in Ymuiden use RADAR information as main tool for traffic
organisation and shore-based pilotage. There is complete RADAR coverage for the VTS-area and RADAR
information is fed into a report- and following system. All information is presented the PONTIS system, a
system for Port Management. AIS information is also used for traffic organization but mainly in the area of
the Port of Amsterdam as there is no complete RADAR coverage.
When asked why RADAR and not AIS information is used in the VTS-system, the answer was that AIS is not
reliable enough. Through the last years the experts had experienced several problems with the use of AIS
information, e.g. wrong time zone, wrong position or even switched off. Further, the expert said that it
might even be dangerous to use the AIS for traffic organisation as the information is updated in different
intervals.
“AIS information does not add anything that one does not know through VHF-communication; it is an
information system, but nothing more”
When asked about additional equipment, the Chief VTS operator mentioned that there was no need for
further technical aids. The information displayed today is already including all necessary information. The
core aspect is to learn the system, not to have more information displayed. Further, estimated arrival time
(ETA), Cargo, TCPA and CPA were identified as the most important information for a VTS operator and it is
already displayed in the system used today. Finally, the windows of the HOC were pointed out as the most
important decision aid for the VTS operators and the shore-based pilots. Through the windows the
operators have a good view on the area and the entrance to the Nordzeekanal.
5.1.3 Training, experience and good service
During the expert group interview, training was mentioned as essential for both shore-based pilots and VTS
operators. They are trained with simulations which recreate the naturalistic environment and are based on
data recorded at different VTS-centres in the Netherlands. All pilots at the HOC have a background as
Master Mariners. They are trained in a national pilot training program. In comparison to the pilots, not all
VTS operators had a maritime background. This is mainly due to problems recruiting new personnel.
“Good service is when no captain is asking questions on the radio”
Concerning good service the operators mentioned the problem that there is no real feedback for when an
operator is doing a good/bad job. It is not necessarily good service just because no collisions are happening.
When asked about the key element for good service, the experts named experience.
5.1.4 Anomalies and near miss situations for VTS/SRS operators
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When asked about anomalies, the experts underlined that there is no clear definition for an anomaly. All
situations differ from each other depending on the traffic density, the vessel’s characteristics and the
mariner’s experience in approaching the harbour. It is hard to say when an anomaly is occurring and what
triggered it.
Concerning the definition of “near miss situations”, the experts’ answer was quite similar. Situations differ
and it can sometimes be appropriate to pass really close to each other. In general there are short distances
in the Dutch waters as there is inland traffic on small channels as well as traffic passing through the VTS-
area both north- and southbound. The passing sometimes is close with less than one nautical mile as
distance between two vessels.
5.1.5 Problems/needs
The experts mentioned several problems they have experienced in their work. Mainly the competence of
the bridge teams was said to be steadily decreasing leading to problems in the ship-to-ship and ship-to-
shore communication, e.g. when talking about a vessel’s intention. Another problem recognized was that
mariners nowadays are less likely to follow the common rules for the traffic at sea. It has been experienced
that vessels give way late in a distance of less than one nautical mile.
5.2 Study visit at the Hook of Holland and Traffic Centre Hook (17th April 2009)
The visit took part during daytime at 17th April 2009. There were 6 participants taking part in the study visit,
two VTS operators/Shore-based pilots from the Traffic Centre Hook (TCH), three shore-based pilots from
the port of Amsterdam and one shore-based pilot from the river Scheldt. The visit started with two
presentations on shore-based pilotage and VTS in the Port of Rotterdam. Each presentation was followed
by a short discussion concerning different aspects of SBP and VTS in the Netherlands. During the
discussions the experts from the different traffic centres acted as a focus group. A question was directed at
them starting a discussion between the experts. The presentations and discussions were followed by a visit
at the Traffic Centre Hook, where all experts participated.
5.2.1 Services and organisation at the T.C.H.
The Traffic Centre Hook contains three different organisations concerned with pilotage and VTS-services.
The administrative staff works with planning and managing the pilots for the incoming and outgoing
vessels. Further, there are pilots and VTS operators working at the T.C.H. During every shift there is a chief
pilot and a chief VTS operator at the centre to manage and coordinate the work of the operators and shore-
based pilots as well as the traffic movements in and out of the harbor. At the T.C.H. the VTS operators are
responsible for information service and traffic monitoring, navigation assistance and advice is reserved for
the shore-based pilots. They are the only ones allowed to advice vessels during their way into the harbor
while the first contact to incoming vessels is normally made by the VTS operator.
5.2.2 VTS operators and workstations
There are four different VTS-areas on the way from the entrance to the Nieuwe Waterweg. The four
operators are located in one room each one on at an own work station (figure 3). The work stations consist
of u-shaped desks with four computer screens, a telephone with touch-screen monitor, a VHF-receiver, a
microphone and speakers. The screens the operators are facing display different kinds of information.
There is one screen showing all information on incoming vessels, one with information on vessels at anchor
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and two RADAR screens showing the VTS-area. AIS information can be displayed on the RADAR. Green lines
mark the vessel which has sent the most recent data update. The interface displays information on the
landscape and coastlines in dark colours in contrast to vessel which are displayed in light colours.
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Figure 4: One VTS operator station at the TCH
5.2.3 Alarms
The VTS-system has different warning systems which are normally not used by the operators. The only
alarm function frequently used is one showing vessels at anchor in a circle. In case a vessel is moving but
has not reported that, the system alarms the operator as soon as the vessel touches the boundaries of the
circle surrounding it. When asked about possible future alarms, the operator stated that he did not think
that this would be necessary. The equipment used today is well enough to monitor the traffic and to
provide good service.
5.2.4 Collision avoidance and safety margins
During the discussion the experts where asked how they would define a near miss and how such misses
could possibly be presented as part of the decision support system they work with it their daily work.
Outside the Port of Rotterdam there is dense traffic with vessels lining up for entering port as well as
vessels passing on their way north and south. Under these conditions it is important to consider safety
margins between vessels to avoid collisions and to guarantee an efficient traffic organisation. When asked
how safety margins are determined the experts answered that those margins are made based on
experiences. This is why one can say that every person/actor, e.g. captain, pilot, port authority, has his/her
own view on the minimal distance a vessel needs to another. Further, safety margins depend highly on
different factors, e.g. vessel size, ability to manoeuvre, weather, experience of crew on board etc. so that it
is hard to define a general safety margin for a situation and vessels.
5.2.5 Planning – short-term, long-term, proactive
Through the VTS-system the operator gets information on the expected vessels. When the vessels enter the
reporting area they are labelled on the RADAR and first contact is established. A first contact normally
contains information on the draught and intentions of a vessel. The operators use a passage plan for long-
term planning. The data of the passage plan can be found in the information system which delivers
information concerning incoming and outgoing vessels as well as those which are at anchor. Through that
system the operators can access the estimated arrival time (ETA) for each ship. That makes it possible to
follow a vessel making its way to the port as all deviations must be reported.
Proactive actions are often coupled with traffic monitoring. As the operator monitors the traffic he/she also
predicts the development of the traffic based on the situation displayed on the screen. One of the experts
also mentioned that there is a track-monitoring function integrated in the VTS-system at his traffic centre
which gives an operator the opportunity to monitor the predicted track of a vessel, but it is never used.
“One needs to have experiences from both sides”
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During the study visit it was stated several time that one needs to have expert knowledge to provide
efficient, safe and reliable service for the vessels in the corresponding VTS-areas.
5.2.6 Communication
All operators in the TCH use the SMCP for communication on the VHF and the communication is in either
Dutch or English. The experts said that communication is the main tool to implement trust between the
operator ashore and the bridge team. To be able to provide good service one needs to trust in the other
party’s competence.
5.3 Study visit at Sound VTS Malmö
On 23rd April 2009 the Sound VTS in Malmö was visited as part of the data collection process. As during
earlier study visits, observations of the operators at work were combined with an expert group interview
concerning the daily work with focus on ship-shore communication and VTS decision support systems. After
an introduction on the Sound VTS and its background, the pilot ordering service and the VTS-service were
visited. During the visits the operators were asked questions concerning their work, equipment and ship-
shore communication.
Sound VTS is not a VTS but a ship-reporting system (SRS) offering information service (SOUNDREP). It
started in 2007 as a project financed by both the Swedish (SMA) and the Danish Maritime Administration
(DMA). The system offers 24h/7d service with two operators in each shift. The reporting system is not
mandatory, but is still covering more or less 96% of all traffic passing through the Sound. Besides the SRS,
the Sound VTS-centre also administers the pilot service, with 28 pilots at 6 different pilot stations. The
pilots are responsible for both long-distance pilotage as well as Sound passages. The area covered by the
Sound VTS today is just a small area but an enlargement is planned for 2012.
5.3.1 The operators at the Sound VTS
The operators work 12 hour shift, changing roles (active, passive) every second hour. When taking an active
role, the operator is at his work station, providing information service and monitoring the traffic. The
operator taking on a passive role is still in the VTS-centre, but he/she is free to leave the work station and
can either take care of administrative work or take a break. During each shift, there is one Danish and one
Swedish operator. Operators work 2 days followed by several days off. The training for a VTS operator
contains an introduction course as well as on the job training. All training corresponds to IALA-
recommendations and the operators have a maritime background as Master Mariners. Experience, both
onshore and onboard, is seen as the key to good VTS-service. One has to understand the needs of the
seafarers to be able to provide good service. Further, it was also stated that it is one’s experience which is
essential for recognizing anomalies in the traffic situation.
5.3.2 Working environment and equipment
The operators are located on the 13th floor with a good overview of the harbour entrance. There are three
desks, two for the operators at work and one for the possibility to raise manning levels if it is necessary.
Each station consists of a slightly u-curved desk, which can be adjusted in its height, five computer screens,
a telephone with touch-screen, a VHF-receiver and two speakers. Three of the computer screens show
RADAR pictures of the Sound, the areas displayed are chosen individually by the operator. The other two
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displays show hydro-meteorological information and a database containing information on vessels which
currently are in the VTS-area.
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Figure 5: VTS operator at work at Sound VTS
Although there are RADAR screens the operators still use the paper chart to look up detailed information
on specific areas, e.g. on cables, offshore installation etc. The paper chart serves the VTS operators as an
additional information source.
5.3.3 Traffic anomalies, near miss and high risk vessels
During the study visit the VTS operators were asked questions concerning the definition and identification
of anomalies in the traffic. They stated that it is hard to define anomalies as there is nothing like typical
situation. Each day different types of vessels pass the Sound carrying different cargo, having different
intentions etc. The traffic development differs from case to case. Therefore it is the operator’s experience
and training which makes him/her recognize a situation, but still it is impossible to define a general case of
anomaly.
As well as anomalies, it is hard to define a near miss situation as it is also strongly related to the situation in
which it occurs. Normally there is not such a high risk for collisions but rather for grounding in the area of
the Sound VTS. There are alarms integrated in the systems signalling that a ship is leaving the
recommended course, but often the operators do not have enough time to help a vessel avoid grounding.
The margins in the Drogden channel are sometimes very small. When talking to the chief VTS operator it
was mentioned that there is the intention to start marking high-risk vessels on the RADAR screen in a
different colour. The category high-risk vessel contains black listed ships, ships with dangerous cargo and
large vessels which are hard to manoeuvre.
5.3.4 Good service
During the expert interview the VTS operators were also asked to define “good service”. For the Sound VTS
good service is defined by the provision of 3 different kinds of information to the vessels in the VTS-area:
- Information to a vessel on possible meetings with other vessels
- Information concerning weather and water level in channels
- Information which cannot be obtained by the information system on the vessel itself, e.g. when a
vessel is about to lift the anchor all the surrounding vessels are made aware of a crossing ship
The operators also mentioned that their work has influenced vessels to report to the SRS because of the
information one can get. Nowadays vessels that are frequently in the VTS-area, e.g. fishing boats, are much
more likely to report themselves than before.
5.3.5 Communication
All operators at Sound VTS use SMCP as well as there are different general procedures which need to be
followed while reporting vessels. Although the experts said that SMCP was always used, they mentioned
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that there are exceptions, e.g. when talking to a “British captain”. As communication is seen as essential for
the information service offered by the VTS, it is important for the VTS operator to adapt the
communication to the different people from different cultures. The working language for the VTS operators
is English which is spoken on channel 17 and 16. Even when a vessel calls in Swedish or Danish the
operators answer in English to be able to provide important information to the other vessels in the VTS-
area. But there is also a working channel, channel 4, which opens the possibility to contact the VTS or the
vessel in Swedish or Danish. Communication seems to be highly coupled with the experience a certain
operator has.
5.3.6 Problems/Needs
There are several problems that the VTS operators experience during their daily work. For example, there is
no possibility to obtain information on the visibility in the fairways. Today visibility is checked by calling the
Drogden-lighthouse. But this means that the information is not updated or called in every hour or in even
shorter intervals, as it would be required for good service. A solution to this problem would be the
installation of CCTV-cameras along the fairways. That would also help to monitor the traffic in the fairways
better. On the RADAR passing vessels in dense traffic actually seemed to collide in the picture as their
plotting overlaps. Another difficulty recognized by the operators was that the reporting of vessel entering
the area is not mandatory. Today all ships passing the reporting line are called and about 96% of the vessels
answer, making it sometimes hard to provide complete information to all vessels in the area.
5.4 Expert Interview with Eric Wagner
To obtain more data concerning VTS in the Baltic Sea Region an expert interview with Eric Wagner was
conducted. As part of the BaSSy project, Baltic Sea Safety, Eric Wagner conducted an operational
experience review (OER) at the Helsinki VTS station. He spent five weeks during late 2005 at the Helsinki
VTS and conducted interviews and observation during day and night and high and low traffic density.
Further, a task analysis was conducted as part of the OER. The goal of the study was to identify possible
human factors design discrepancies in the system. The operational experience review focused on four
different areas: the socio-technical system, the control room, the workstations and the software system
used for VTS-services. A so called compliancy checklist was used to evaluate the four areas. This checklist
was based upon different ISO, IALA and IMO standards and guidelines providing the baseline criteria to be
met.
5.4.1 Service and manning levels at Helsinki VTS
Helsinki VTS offers 24 hours of service seven days a week. The operators work in 12 hour shift. There are 38
operators working at the VTS Helsinki. There are two different services at the traffic centre, GOFREP, the
Gulf of Finland Mandatory Reporting System, and the VTS sectors which are responsible for traffic
organisation, information service and navigation assistance within the Finnish territorial waters and VTS
sectors. As VTS-services in Finland were centralized several years ago, the optimal work situation is seven
operators working at one time; one chief operator, one for the Kotka area, one for Hanko, one each for the
Helsinki east and west sectors, one for the Helsinki approaches (up to berth), one GOFREP operator and
one backup operator as well as the watch supervisor. The two operators in the Helsinki area change with
one another regularly during their shifts as well as the GOFREP and the Hanko operator who change every
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fourth hour. This is meant to relieve the operator from fatigue in monitoring high traffic areas by letting
them switch to a lower traffic intensity sector for a period of time.
The GOFREP operator at the Helsinki VTS station is responsible for monitoring the traffic entering and
transiting vessels within international water on the Finish side of the Gulf of Finland while the VTS sector
operators have several tasks in addition to the “primary” traffic monitoring task such as arranging the ice-
breaking service within the harbour basin, managing vessel departures and arrivals. Outside of normal
office hours the VTS operators also organise the traffic in the port such as where to berth etc., arranging
stevedores and receiving the fire and break in alarms for the port authority installations. On top of that the
filling in of maintenance request reports for i.e. faulty or malfunctioning aids to navigation, radars etc is a
part of the VTS operators’ daily work.
5.4.2 The VTS system
The computer system used for monitoring traffic is standardized and it is used for both the sector VTS-
services and for GOFREP. It is an electronic chart and information system (ECDIS) with integrated AIS and
RADAR information. The electronic chart system displays the VTS sector area approaches on one display
and detailed hot spots on another display located at the work station. Additionally there are large screen
displays for GOFREP and each sector workstation showing the entire sectoral area of responsibility for that
operator. During observations the expert recognized that the amount of information displayed in the
electronic chart system was reduced to just the most necessary information, e.g. name of vessel.
Extraneous information such as soundings, navigational aids etc. were not displayed. This would otherwise
contribute to highly cluttered displays complicating target vessel monitoring.
Further, the system is used in conjunction with other databases, e.g. FMA’s vessel database, Lloyds register
database, PortNet etc. Eric Wagner found that the frequency of use of the information sources differed
depending on the situation and the tasks at hand for an operator. In addition to the electronic traffic
monitoring support system the expert recognized that the operators used paper charts to obtain more
detailed topographical information if required. When asked about which decision aid was most important
for the VTS operators, the expert answered that this was hard to define. Traffic monitoring is of course the
primary task. The usefulness and importance of a tool depends on the task situation and the VTS area. For
example, it was observed that the VTS operators worked a great deal with the PC based ancillary
applications for administrative tasks or in order to obtain further information from different databases
regarding a vessel. For the monitoring of traffic the more important functions used included the predictor
vectors, TCPA and CPA.
5.4.3 Alarms
The VTS traffic monitoring system at the centre had different alarms function which tended not to be used,
mainly because too many alarms would be generated which can be very distracting for the operator. There
are many narrow fairways and small islands along the coastline of Finland. This leads to situations in which
vessels need to pass close to each other generating an alarm although no serious problem is occurring.
There were several other alarm functions; e.g. a CPA/TCPA alarm provided in the system to determine close
passage, but it was not often used mainly because it was somewhat difficult to execute. Eric Wagner also
mentioned that there were alarms and functions supporting risk assessment of different situations, but
that they were too “hard to find” in the menu based interface.
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5.4.4 Experience
As during earlier interviews for this study, Eric Wagner also mentioned that experience is essential for the
decision making process of a VTS operator. He observed for example that VTS operators could determine if
the AIS information displayed such as draught seemed plausible for the vessel’s other characteristics. The
expert also mentioned that the operators search for patterns in the displays to be able to match the
response action to the situation displayed.
5.4.5 Problems/Needs
The operators were missing a function to mark different vessels as carrying high risk cargo. As there was no
information coding function to display dangerous cargo, it took extra time to click on each vessel to obtain
cargo information manually. Further the expert recognized that the operators at the VTS Helsinki had a
number of different tasks which were not necessarily related to the primary VTS task; information service,
traffic organisation and navigation assistance.
5.5 Focus Group Interview
Eight VTS operators, seven male and one female, participated in the focus group interview. They all were
currently taking a course for supervising new VTS operators during the on the job training. They all had
several years of work experience and worked with providing VTS for different areas (Archipelago, Helsinki,
Hanko, Bothnia, Lake Saimaa) as well as with the GoFREP.
5.5.1 Questions
Three main questions were asked during the focus group interview. They were presented separately and
discussed one at a time.
1. Rank the following decision support tools according to their importance for your daily work! Which
one is most important, which one least?
2. What characterizes a conflicting situation?
3. How would you define “good VTS-service”?
5.5.1.1 Question one: Ranking of Decision Support Tools
In question one the VTS operators were asked to rank the decision support tools according to their
importance for their daily work. Table 2 shows the result of the individual ranking and the group ranking of
the operators.
Table 2: Ranking of Decision Tools
Decision Support Tool Individual Ranking Group Ranking VHF 1, 4 2 RADAR 1 1 ECDIS 2 4 AIS 3 3 CCTV 5 Databases (PortNet, PilotNet, Lloyds) 5 Hydrographic and meteorological information 6 Telephone, GPS, Internet Not ranked
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When the individual ranking was discussed the group mainly shared the same opinion. A discussion came
up when the importance of the RADAR and the VHF was ranked. Both tools were thought of as being very
important for the daily work of an operator, although the participants could not agree on which of them
was most important.
“Man måste se var de kör” (You need to see where they are going)
“Utan VHF kan man inte göra nåt” (Without the VHF you are not able to do anything)
After the presentation of the individual ranking the group was asked to create a ranking together. RADAR
and VHF were ranked most important and the experts stated that those are the tools that are essential for
being able to provide VTS. The operators stated preferring ECDIS, AIS and RADAR as an integrated system
instead of having the information displayed separately. Internet, hydro-meteorological information and
databases were seen as equally important and are used frequently. They are seen as connected to each
other as e.g. internet is needed to be able to access databases such as PortNet, PilotNet etc. Cameras
(CCTV) were rated as not so important for the provision of VTS. One operator stated that they might be
needed when the visibility is low in the areas. Another opinion was that cameras would useful if installed at
the pilot boarding points.
As a follow-up the group was asked about which particular information presented by the system, they use
in their daily work. Some of the operators stated that all information that can be obtained by the system is
used. However, as during earlier expert interviews, the participants in the focus group underlined that the
need for information differs depending on local conditions in the VTS area. An example is the use of AIS-
data.
• VTS Helsingfors & VTS Kotka: name, speed, course and heading
• VTS Botnia: name, destination
• VTS Archipelago: name, speed, course, heading and destination
• GOFREP: uses all AIS-data which is transmitted
5.5.1.2 Question two: Conflicting Situation
The second questioned aimed to get a deeper understanding of problems and difficulties that VTS
operators might experience in their daily work. As before the participants were first asked to work
individually and then to discuss the individual answer in a group. A white board was used to take notes for
further discussion. There were several different categories of conflicting situations.
• Deviation from the fairways
• Technical problems
• No common language
• Different opinions in a situation
• Tired Staff
5.5.1.2.1 Deviation from the fairway
Deviations from the fairway are normally recognized while monitoring the traffic on the ECDIS. There is no
further tool the experts could think of which could be used to facilitate the identification of such deviations.
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5.5.1.2.2 Technical Problems
Technical problems were also identified as conflicting. The system used for VTS in Finland integrates
different information sources in one system. That makes it hard to monitor if the system is working
properly; e.g. it was mentioned that it is hard to know where the information actually comes from. That can
lead to situations where RADAR stations are not working properly but it is not noticed by anyone as there is
still the AIS information in the system. Technical problems were also identified as hardest for a new
operator. When one is not used to the system it is hard to be able to solve any problems with the
equipment on his/her own. One needs to have experience.
5.5.1.2.3 No common language
In the Gulf of Finland lots of international traffic passes each day. There have been communication
problems as there is a lack of a common language. This is especially a problem if a vessel has pilot
exemption certificate. This can result in a vessel e.g. vessels with Swedish manning where no one speaks
Finnish where the VTS operator needs to translate information between one vessel and other vessels. The
Finnish VTS operators use message makers to facilitate the communication. The lack of a common language
was also identified as especially hard for a new operator. There is no part in the VTS education which helps
to handle situations where communication is not working due to different languages.
5.5.1.2.4 Different opinions in a situation
There are conflicting situations which occur due to different opinions of the multiple players involved in the
maritime sector. One is example are differences between the personnel on board a vessel and the VTS
operator. Especially during difficult conditions, e.g. bad weather, both operator and bridge team may have
different opinions on the situation and are eager to only trust their own instruments, making it harder to
cooperate. Other conflicting situations can occur when pilots and VTS operators have different opinions.
Nowadays there is no interpersonal contact between the VTS operators and the pilots which can lead to a
loss of trust.
5.5.1.2.5 Tired Staff
There have been problems with tired staff on board of vessel. The experts mentioned that it is possible to
identify if a person is tired or not depending on the way he/she communicates with the operators. This is
especially hard as the operator cannot do anything. In addition, follow-up questions concerning workload
and information load were asked. The experts stated that there are different distractions. An example that
was pointed out, were alarm functions. There are a lot of different alarm functions integrated in the VTS
system which are either turned off or ignored (also mentioned by Eric Wagner).
5.5.1.3 Question three: Good VTS service
The third question focused on a definition of good VTS service. The operators stated different aspects of
good VTS service:
• The technical equipment should be good and working containing the decision tools mentioned in
question one
• Satisfied VTS staff
• Clear rules for the interaction between VTS operators and the different clients, e.g. agencies,
vessels, ports
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• High degree of domain knowledge
o Operators should have a background as a mariner to be able to handle different kinds of
situations
o The operator should participate in refresh-courses to gain new knowledge
o On-the-job training
• The traffic is fluent without any congestions
• The personal chemistry between the different players (VTS, pilots, vessels etc.) in the maritime
sector is good
5.6 Expert interview with Adam Cowburn
As part of this study Adam Cowburn was interviewed. Adam has a background in behavior science and
communication and has been working with the education of VTS operators for the Swedish Maritime
Administration. The interview followed an interview guide with focus on the education and communication
of VTS operators.
The Swedish VTS operators are educated according to IALA guidelines and recommendations. There is a lot
of practical training in a simulator. Additionally there are different educational blocks in which
communication, speech and service (attitudes) are trained. When asked about possible improvements in
the education of VTS operators, the expert mentioned that there is a need for more explicit guidelines on
what should be included in it. Nowadays the recommendations from IALA are quite openly formulated not
leading to any specific education but to a system where the education of operators differs from country to
country, and sometimes even from one VTS centre to another. Further, the expert mentioned that there is
a need to improve the SMCP phrases used in the VTS domain. Today the phrases are too many and they are
not as standardized as in similar domains, e.g. aviation. Communication needs to be handled as a process
supported by the phrases. Therefore there should be fewer and more directed phrases which are trained
thoroughly throughout the education of an operator.
According to Adam Cowburn there are several organisational aspects that can influence the decision
making of a VTS operator. There is, for example, no common knowledge of the work of VTS operators in
the maritime community. Sometimes VTS is seen as pilot ordering service (POS) or maintenance service for
aids to navigation (which has also been mentioned by Eric Wagner). Therefore there is the need to
formulate safety as main goal for the VTS so that it becomes clear what functions the operators actually
have. However, this change in attitude needs to be built on a better cooperation between the different
actors in the maritime sector, e.g VTS operators, pilots and seafarers. Further, there is the need for better
briefings and checklist in the daily work of operators based on international standards which make it clear
which parts are included in VTS and which are not. When asked about the definition of good service, Adam
answered that good service is based on that a positive attitude towards communication and process
thinking. An operator needs to monitor the traffic actively combined with having good knowledge and
understanding of the maneuverability of vessels and possible actions which can be taken by a bridge team.
As possible improvements of the VTS, the expert mentioned that there is the need for a longer education
coupled to a better recruitment. Although VTS operators are supposed to be trained Master Mariners there
is a lack of practical knowledge of maneuverability of vessels well as possible actions which can be taken.
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Further, the communication skills of the operators need to improve with more focus on how standard
phrases can be used as part of a process. Finally, the VTS needs to be defined in one term, eliminating all
the different acronyms used today. VTS has to be a service with the main goal to improve the safety at sea,
not just something that is seen as pilot ordering service.
5.7 Result eSim
As part of Work Package 4 a day in the Sound was simulated. Experts participated in the simulation acting
as close to their daily work routines as possible. During the simulation the expert acting as VTS operator
was observed for data collection. The VTS operator was an experienced Danish operator from the Sound
VTS in Malmö. He acted as professional and tried to work as close as possible having in mind that there
were several technical limitations. The equipment for the provision of the VTS was limited to one ECDIS
display and a paper chart. There was no possibility to use any databases or the internet to obtain
information incoming vessel. Further, there were UHF used as VHF and the VTS operator had only one VHF
to work with. Additionally to the VHF, there was a mobile phone which could be used for contacting any of
the other players in the scenario. Several results concerning the work of this work package could be
observed.
5.7.1 Planning
There were different activities observed which the operator himself called for proactive actions. These
actions were for example to zoom in on hot spots and on the reporting line. The operator motivated his
actions by work experience from his daily work. Another proactive planning activity was to confirm the AIS
information with the vessels. This is important in the Sound as the maximum draught for the two channels
(Drogden, Flint) differs.
5.7.2 Equipment
During the simulation the VTS operator mentioned several times that the technical equipment is essential
for the work of an operator. He stated that there is always the need for at least two displays, one showing
the whole area, one showing the hot spots, to be able to provide good service for the vessels in the Sound.
In the simulation the operator was forced to choose between zooming in on different spots or seeing the
area as a whole. Further, the simulation showed the need for the access to different databases. As the
operator could not use the internet connect to different databases he constructed his own database on a
piece of paper showing all vessels currently in the area including their maximum draught, their intentions
for passing the Sound and their destination.
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6 Analysis and Discussion The overall aim of this study was to identify user needs of VTS operators with regards to decision support
tools used today for providing vessel traffic service, and to get insights on these user needs for the
technical development of future decision tools. Three research questions were formulated and each one is
going to be analyzed and discussed separately.
6.1 What characterizes the decision making in the settings of a VTS centre?
The decision making at a VTS centre is characterized by what Klein (1993) named “simple match” (variation
1) and “diagnose the situation” (variation 2) in the RPD model of naturalistic decision making. VTS
operators act based on experience, making it hard to actually single out different aspects that influence the
decision making. There are different situations which are seen as typical and where the operators act on
earlier experiences, creating a framework consisting of expectancies, cues, plausible goals and typical
actions.
6.1.1 Traffic Monitoring
During traffic monitoring the operators look for information that conflicts with the expectancies they have
on the traffic development. Depending on the contextual setting, e.g. what services a VTS centre offers, the
geographical conditions, traffic density etc., there are different cues in the information presented on the
display that the operators act on. Based on their working experience, both on board and on shore, the
operators have concepts on what is typical and what is not. As long as all the information is classified as
typical, their course of action is to let the traffic flow without interfering actively. This was especially
obvious when the Sound VTS was visited. As a ship reporting system the Sound VTS calls every vessel that
enters the area. In the VTS centre the operators use different screens for collecting information and getting
cues on how the traffic is developing. As soon as a vessel passes the reporting line, the operator calls it on
the VHF radio. Even if a vessel is not answering, the situation is not necessarily seen as atypical as the
system in the Sound is not a mandatory one. In the case of the Sound, the passing of the physical reporting
line on the screen by the ship representation on a display is seen as a cue to act on, resulting in the
operator calling the vessel. The goal of the call is to get in contact with the vessel as well as confirm
information reviewed on the system, e.g. maximum draught.
6.1.2 Information Service
The information service also seems mainly based on simple match decisions. The information from
different data sources is used to construct a dynamic picture of the situation. Based on their experience the
operators use the information as cues to act on. The information presented is matched against their own
expectancies. The goal of the service is defined as giving the right information in good time. Acting on the
situation, the operators make the decision on which information is needed by whom and when.
6.1.3 Navigational Assistance
Navigational assistance is based on what Klein (1993) calls “diagnose the situation” (variation 2). As
mentioned above, in this variation of the RPD model the operator needs to address the situation actively to
determine a course of action, in this case giving the right advice and assistance for the vessel in question.
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To be able to assist a vessel with navigation the operator needs to infer more data from the context. This
might, for example, happen through conversations on the VHF working channel in the area where the
responsible VTS operator asks the bridge team for complementing information. The communication is not
only used to define what kind of advice or assistance a certain vessel needs. It is also used to derive
information on the status of the bridge team, e.g. shore-based pilots in the area of Ymuiden and Rotterdam
use the communication to decide if there is the possibility of giving shore-based pilotage to a vessel.
What makes the decision making process of navigational assistance different from the one of information
service and traffic monitoring is that the operator needs to take both the bigger picture and the immediate
surroundings into concern while assisting in someone else’s decision process instead of just matching a
response to a typical situation. This means he/she needs to assess the situation without taking over control,
matching the advice or assistance to a specific vessel in a specific context. Further, in the case of
navigational assistance and advice it also seems like mental simulation is used to determine the best way to
assist the bridge team. Based on own experience the operator tries to derive how he/she would act in the
situation of the bridge team. This is done by imagining a course of action.
6.2 What decision support tools are used today to provide vessel traffic service?
There are several different decision support tools used today to provide vessel traffic service. The most
common have been listed and described above. Through several expert interviews, observations and a
focus group interview it became clear that the use of decision tools is highly dependent on contextual
factors such as:
• Services offered by the VTS in the specific area
• Traffic density
• Geographical and hydro-meteorological conditions
• Manning levels
• Level of education and work experience of the operator
This can be explained by the need of information that the operators have at different VTS centres. Through
the study it became obvious that the needs for decision support tools can be different from one VTS centre
to another due to contextual differences. In some areas VTS operators also had to take responsibility for
tasks not necessarily included in the definition of a VTS, e.g. the VTS operator for the Helsinki area is also
making maintenance reports on aids to navigation as well as managing the traffic organisation up to berth
outside of the port’s office hours. This makes it quite hard to define which decision support tools are
actually used and needed for the provision of VTS in a VTS area.
However, the results of this study show that most essential for a VTS operator is the VHF and the RADAR.
Those two tools were used in a more or less integrated system in each VTS centre that was visited.
Additionally, these two tools were also named to be indispensible in the focus group interview and should
always be working. Further, parts of the AIS information transmitted were also identified as important for
the provision of good VTS service, e.g. CPA, TCPA, name, course and ETA. But nevertheless, all the experts
mentioned that there were problems with the reliability of AIS data displayed in the system. Too often
experience had shown that the information transmitted through the AIS was wrong. Based on that
experience the operators had problems trusting this information and it was therefore handled very
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carefully in the decision making process. In a worst case scenario, all information derived through AIS needs
to be confirmed by calls on the VHF leading to a high amount of additional communication, which might be
a problem in areas with high traffic density.
Further, the use of decision tools also seemed to depend on how integrated a certain tool was into the
system. Some of the operators mentioned that it was not possible for them to say if they were using AIS or
RADAR as both information sources were integrated in an electronic chart and information system
displaying all data in one chart without showing where the information actually was coming from. Finally,
the data collected in this study indicates that one of the key elements in the decision making in a VTS
centre is not any specific tool, but rather the experience the operators have. Experience in this case
includes both experiences as a VTS operator and as an active seafarer to be able to determine a course of
action for a specific situation. This is especially important when an operator needs to give navigational
advice and assistance as well as in cases such as a vessel leaving the fairway or vessels getting too close
each other.
6.3 What user needs do VTS operators have today and how can these be included in
the decision support system development of the future?
The results of the data collection indicated that there were two different categories of user needs:
• Organisational user needs
• User needs concerning the technical system
The focus of this analysis was on using the definition of usability according to the ISO-standard 99241-11 to
develop user needs that might guide future decision support system development. As mentioned earlier,
this study focused mainly on user satisfaction and the context of use, not on efficiency and effectiveness of
the systems used for providing VTS, due to the big differences between the different VTS centres that were
studied.
6.3.1 Organisational user needs
The first category of user needs that could be identified was organisational user needs. This user category
contains all aspects that were named regarding the organisational setting in which the VTS operators work
including education and training as well as attitudes towards the VTS as an institution.
The maritime sector is an international work environment where people from different cultures interact on
a daily basis. For VTS operators this means they need to adjust their behaviour based on service promoting
safety at sea. The VTS is often seen as POS or maintenance service for the fairways and aids to navigation.
Therefore there is the need to establish a better cooperation between the different actors in the maritime
settings taking into account that each person has a concrete role connected to specific assignments. There
is a need for international guidelines that define more thoroughly what services are included in VTS and
which are not in order to change the attitude towards the VTS. The VTS is an active information source and
should not be used as e.g. berth organizing service.
Further, according to our experts, the decision making is complicated by the fact that the competence of
the bridge teams seems to be decreasing. The experienced VTS operators especially mentioned decreased
navigation and communication skills making the interaction between shore and ship more complicated.
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Therefore one can state that there is an urgent need to formulate guidelines to guarantee a certain level of
education for both seafarers and VTS operators. Additionally the number of acronyms describing the VTS in
the international maritime community needs to be limited. Nowadays there are several acronyms (e.g. VTS,
VTMIS, VTMS) describing the services offered. There is the urgent need for a standardization of terms to
make a clear statement on what VTS can provide.
6.3.2 User needs concerning the technical system
The VTS operators from different VTS centres mentioned several aspects that can be defined as user needs
regarding the technical support systems used in their daily work.
Through observations and interviews it became clear that one problem with the decision support systems
used today for providing VTS is that the design did not always take into account how people make decisions
under time pressure. As shown above decision making in naturalistic settings is not based on a deductive
deliberation process considering different options. Instead, a course of action is chosen based on
recognizing patterns and then deriving a course of action based on those patterns. Operators neither
consider all possible actions nor the optimization of the outcome. Therefore there is a need to focus on
what data is needed to support the operators’ decision making in specific contexts rather than presenting
much data on a screen.
Further, there is the need to consider the complexity of the decision support systems implemented in the
VTS. Some VTS operators commented that there is plenty of superfluous information in the system, and
only a minor part of what is available is used on a regular basis. However, unless the system is adequately
designed, an increased amount of information tends to also make it harder to access, find, and utilise the
most relevant information. It seems that the decision support systems in use today are already complex
enough to interfere with the operator’s work processes. This implies that only functions that are
considered relevant by the users of the system should be implemented or be a subject to testing in a
specific context. Another user need is the need to be able to oversee the level of data integration in the
support systems. The experts mentioned that they must be able to trust the reliability of the information
displayed in their system. This is not possible if one does not understand where the information stems
from. An example named was the integration of RADAR and AIS information in one system. The operators
could not differ between those two sources, to judge their individual reliability, as the information was
integrated in one display.
6.3.3 Indications for future development
When designing a new decision support system for VTS operators, one needs to bear in mind that risk is
defined on an individual basis by each operator, there is no such thing as a general description of risk and
people can have very different opinions on, for example, risk for grounding or collision. Therefore it does
not seem meaningful to compute risk based on parameters such as distance between vessels, speed,
course etc. Rather than calculating risk, the risk assessment of the VTS operators should be supported by
first defining and then presenting the information that is needed for this kind of assessment. One specific
example could be to mark high risk vessels on the display. First, one needs to define the criteria for the
identification of high risk vessels. Those vessel included in this category might be vessels that are black
listed, vessels with high risk cargo, vessels do not following the rules (e.g. COLREG, SOLAS, IMO
regulations), vessels not communicating with other vessels or shore etc.
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7 Conclusions
In this final chapter the conclusions and recommendations of the study will be briefly presented.
7.1 Trustworthiness
Many operators expressed concern with regards to the trustworthiness of the information displayed in the
system, in particular with regards to AIS-based information. It is very important that operators can rely on
the information on which they base their decisions. Concern over the trustworthiness of a data source
leads to a time-consuming process of double checking the information, e.g., asking all vessels for their
present maximum draft over VHF even though this information is nominally available via the AIS. If the
reliability of a data source cannot be guaranteed, it is perhaps more suitable to remove it from the system
altogether.
7.2 Information presentation
The VTS operators emphasized on that it is important that the right information is presented at the right
time. What information and when this is, depends on the context of use, e.g. traffic density, geographical
and hydro-meteorological conditions. The amount of information should be limited to just what is
necessary for the daily job of an operator. Future support system design should bear in mind that decisions
are often made based on pattern recognition. It is therefore important that pattern recognition and other
aspects of the actual decision making processes of the operators and the settings in which this process
takes part are taken into account when designing new decision support systems. Additionally, the experts
stated that problems in the interaction between shore and ship arise by having differences in the
information displayed on shore and on the bridge. There is a need to compensate for, or otherwise
manage, these differences to facilitate the work of the VTS operator.
7.3 Organisational needs
In the study aspects concerning the overall organisation of the maritime sector arose. It became clear that
there is the need to define a general goal and an overall scope for the work of the VTS. The main goal
should be safety, which the organisation of the maritime sector should be aware of this; creating a safety
framework of guidelines which is VTS-centred. This includes, but is not limited, to a clear statement of
which services are included in the VTS. A VTS centre should not become an overall service centre for all the
events happening in a VTS area, e.g. VTS operators should not be forced to take fairway maintenance
records, answer to port alarms, organise the berthing of ships etc.
In addition to a re-organisation one should also state clear guidelines concerning the VTS education. The
background as a Master Mariner needs to be obligatory for all VTS operators. Communication skills and
navigation knowledge need to be improved and renewed frequently to guarantee the best preconditions to
provide good service to the maritime community. Further, VTS needs to be part of the process of safety
management in the maritime sector. This process is relying on the cooperation of many different players,
e.g. agencies, pilots, lock masters, port operators. To accomplish a better cooperation as well as a deeper
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understanding for each others’ work, the different players of the maritime sector should have combined
training sessions.
7.4 Summary of needs
1. Support familiarity in the information presentation to facilitate pattern matching for quick and
effective decision making
2. Support of communication to facilitate the interaction of the different players in the maritime
sector.
3. Support the building of trust through better and more effective communication between shore
and ship (content is more important than quantity)
4. Re-evaluating and defining the role and tasks of the VTS as service for the maritime community
with safety as the main goal
5. Need for a common “situation picture” so that bridge team and VTS operators can perceive the
same representations
6. Remember the non-technical resources such as experience, training, co-workers and
procedures
7. The validity and integrity of the data presented in the system must be guaranteed
7.5 Future Research
For continued work within this area, two approaches are suggested. First, more concrete user needs for
VTS operators and operations can be determined to further guide the development of new decision
support tools. This can be achieved by gaining a deeper understanding of the processes by which VTS
operators perform their work, and in particular of how safety is created in day-to-day work. A possible
method for this can be to perform detailed task analyses of VTS operator work, together with additional in-
depth interviews with operators and scenario-based simulations.
Second, usability evaluations of various suggested decision support tools can be performed. Such
evaluations aim to examine to what degree a prototype decision support tool is usable for the work and
work context it is designed for, and can provide very valuable feedback to the designers.
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